For samples of Tasman and Caxton effluent at several dilutions, the continuously stirred EBOD method gave higher biodegradation rates and higher BOD ultimate values than the standard dilution BOD method. The difference in BODu was 42% for a sample of Tasman effluent diluted 1:4. For Tasman effluent increasing the dilution increased the estimated BODu for both EBOD and dilution BOD method. Both effluents were nitrogen deficient for optimal assimilation rate.